1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method and a storage medium, and more particularly, to an image processing apparatus, an image processing method and a storage medium, which are applicable to a wide variety of types of sources such as a still image and a moving image and which allows an edge of an image to be redrawn into a natural, clear, and beautiful form which gives a good visual impression to a human user thereby obtaining a high-quality and high-resolution image.
2. Description of the Related Art
Devices for dealing with a digital image (such as a digital camera and a video camera including a camera and a video tape recorder integrated into a single device) have become very popular. As a result, a need has arisen for a digital zooming process, and various methods for increasing the resolution of a digital image have been developed. In particular, three methods described below are known. A first method is a zero-order-hold interpolation method in which interpolation is performed by directly using nearest neighboring pixels. The advantage of this method is that interpolation can be performed using simple hardware.
A second method is a bilinear interpolation method in which the mean pixel value of two nearest neighboring pixels is calculated and the resultant value is used to insert a new pixel in the vertical and horizontal directions. Thus, this method is suitable for interpolation of adjacent pixels.
A third method is a B-spline interpolation method which allows an image to be interpolated without creating noise or a mosaic pattern.
However, the first method is not effective, in particular, when an image is enlarged by a large scaling factor, and an enlarged image includes noise well known as a “mosaic” pattern. Besides, an edge is destroyed to a large extent and very ugly jaggies appear.
The second method has the disadvantage that the resolution of an image is not increased and thus the image is blurred over the entire area thereof. In particular, when an image is enlarged by a large scaling factor, a significant mosaic effect occurs.
In the third method, an image is blurred to a rather large extent, and relatively complicated hardware is needed.